I'll be flying as follows shortly (in Business Class):

Brussels > Toronto (via Montreal)
Toronto > Vancouver
Vancouver > Chicago
Chicago > Brussels

It seems I could operate this route via Brussels Airlines of Air Canada. Which would be more interesting in terms of mile collection - Lufthansa/Miles & More, or Air Canada's Aeroplan?

In case you need the info, the business class fare type at AC would be Z, for Brussels Airlines it would be P.